Previously, many types and styles of line stretchers have been used in endeavoring to provide an effective means to stretch a line or alignment cord from the corners of building blocks during the building process. From antiquity, masons have used lines or cords to establish a straight row of building blocks, however, progress has changed only the sizes and styles of blocks with the basic requirement still remaining unaffected. Prior art has utilized devices, such as elaborate line stretching gauges with vertical standards to simple wedge shaped corner grasping holders, with others tightening the line with threaded screws and wing nuts or winding blocks. Others employed ratchet wheel drums for tightening the lines and sliding plates, and the like, which function properly but have a tendency to be complex and cumbersome.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however, the following U. S. patents were considered related:
______________________________________ U.S. Pat. No. Inventor Filing Date ______________________________________ 3,698,089 Huston Oct. 17, 1972 2,919,489 Espinosa Jan. 05, 1960 2,215,663 Frisk Sep. 24, 1940 1,234,282 Butler Jul. 24, 1917 391,496 Vogelsong Oct. 23, 1888 ______________________________________
Huston teaches a slotted clamp having a pair of screws, with washers and wing nuts, positioned in the slot. The screws grip each side of a building block and are adjusted by tightening against each edge. The guide line is held in place between a flat and dished washer and the cord is secured at the opposite end by winding around the screw between the washers.
Espinosa clamps the holder to a block with a movable plate member on one side and a fixed plate on the other. The adjustment is made by sliding a movable section with longitudinally extending ribs and locking it into place with a thumb screw. A ratcheted wheel drum retains the line and is held taut by rotating the handle of the drum until tight and utilizing the ratchet to provide securement.
Frisk grips the block with offset grapple lugs on one end and adjustable anchoring lugs on the other. The adjustment, again, employs the use of a wing nut with a stud that may be passed through either of two longitudinally spaced holes. The anchoring lug is notched, allowing the line to pass unobstructed. A take-up block allows the line to be secured and wound thereupon. Final anchoring of the bars is accomplished by the tension on the line rocking the bars on the engaging end producing the wall gripping action.
Butler employs a wedge driven into a wall attached to a standard. A bracket is slideably mounted to the standard and held in adjustment by a set screw. A series of notches are located in a gauge plate and the line is passed through the proper notch. The gauge plate and line are moved upward as successive courses are laid.
Vogelsong, over a century ago, utilized a bladelike pin sharpened on one end with a shoulder projecting at right angles forming an enlargement. A recess is formed into the enlargement allowing the device to be used on corners. A hole is provided near the shoulder through which a line is passed with a V-groove gripping the line.
Some commercially available line stretchers today are either sized to fit a particular block, or are adjustable by using a wing nut and bolt with mating holes. The line is wrapped around protruding appendages and the tension of the line cocks each tensioner toward each other locking them into place.